I realize the locking mechanism in “P” prevents the car from moving but how does it move in “D” in the first place? The car is turned off! There is no ignition to the engine!
In: Engineering
Some good answers here, let’s get a tiny bit more specific and ELI5.5 Your engine is a bunch of mechanically moving parts. If you yanked your engine out of the car and put a long bar connected to the back or front of the engine, you could manually make the internals move. (Breaker bar on the harmonic balancer or flywheel) From experience, a smaller engine is easier to do this with than a larger one because more surface area = more friction.
So… back to your question. If a car is in “D” then the transmission is in gear, meaning the wheels are connected to the engine internals physically through the transmission. When you are in P or N, the transmission separates the engine from the wheels physically. So if you are in D with the car off and you want the car to move – push it hard enough and it will. Or… use gravity by letting a few thousand pounds and an angle to work out the math for you. 😉
Now… ELI6, you may not actually be making the engine move as other people noted. An automatic car has a torque converter which is a fancy device filled with fluid. This plays the role of a clutch via fliusld pressure. At low speeds with the car off and in D, you are likely to only be spinning the fluid a bit. Either way – this isn’t particularly healthy for the car, so please don’t go around doing this intentionally unless you enjoy repair bills.
Latest Answers